AD 2002-23-21 Airworthiness Directives; Boeing Model 747 Series Airplanes

Models named: 747 series. Read the applicability below — it usually turns on serial or part numbers too.

Model 747 series airplanes, as listed in Boeing Service Bulletin 747-57-2256, Revision 3, dated June 21, 2001; certificated in any category. Note 1: This AD applies to each airplane identified in the preceding applicability provision, regardless of whether it has been modified, altered, or repaired in the area subject to the requirements of this AD. For airplanes that have been modified, altered, or repaired so that the performance of the requirements of this AD is affected, the owner/operator must request approval for an alternative method of compliance in accordance with paragraph (f)(1) of this AD. The request should include an assessment of the effect of the modification, alteration, or repair on the unsafe condition addressed by this AD; and, if the unsafe condition has not been eliminated, the request should include specific proposed actions to address it.

Required as indicated, unless accomplished previously. To find and fix discrepancies of certain bolt holes of the fail-safe bar of the flap tracks of the wing trailing edge flaps, which could result in separation of the flap and consequent loss of control of the airplane, accomplish the following: Restatement of Certain Requirements of AD 91-03-17 Inspections (a) Prior to the accumulation of 30,000 total flight hours, or 8 years time-in-service on current production flap tracks, whichever is first; or within 2,000 flight cycles after March 11, 1991 (the effective date of AD 91-03-17, amendment 39-6884); whichever is later: Perform a borescope inspection of the forward four bolt holes on each side of the affected trailing edge flap tracks for corrosion and adequate cadmium plating, in accordance with the procedures specified in Boeing Service Bulletin 747-57-2256, dated March 8, 1990; Revision 1, dated November 15, 1990; Revision 2, dated March 5, 1992; or Revision 3, dated June 21, 2001. If the cadmium plating is adequate, as specified in the service bulletin, and no corrosion or cracks are found, no further action is required for this paragraph. If the cadmium plating is not adequate, or if corrosion exists in any bolt hole, prior to further flight, conduct an eddy current inspection of the bolt hole for cracks, in accordance with the service bulletin. After the effective date of this AD only Revision 3 of the service bulletin may be used. Corrective Actions (b) If the cadmium plating is not adequate and no corrosion or cracks are found during the inspection required by paragraph (a) of this AD: Within 1,000 flight cycles after accomplishment of the inspection required by paragraph (a) of this AD, cadmium plate the affected bolt holes in accordance with Boeing Service Bulletin 747-57-2256, dated March 8, 1990; Revision 1, dated November 15, 1990; Revision 2, dated March 5, 1992; or Revision 3, dated June 21, 2001; and conduct the inspections of the affected track as specified in paragraphs (b)(1), (b)(2), and (b)(3) of this AD, in accordance with the service bulletin. Restoration of the cadmium plating terminates the inspections required by this paragraph. Inspections (1) Within 50 flight cycles after accomplishment of the inspection required by paragraph (a) of this AD: Perform a close visual inspection of each side of the track, at the lower chord, for cracks emanating from the forward four fail-safe bar bolt holes, and repeat the inspection thereafter at intervals not to exceed 50 flight cycles. (2) Within 250 flight cycles after accomplishment of the inspection required by paragraph (a) of this AD: Perform an eddy current inspection for cracks of the bolt holes, and repeat the inspection thereafter at intervals not to exceed 250 flight cycles. (3) Prior to each flight on which a fifth engine is to be carried, perform a close visual inspection of each side of the track, at the lower chord, for cracks emanating from the forward four fail-safe bar bolt holes. New Requirements of this AD Cadmium Plating Applied During Production (c) For airplanes on which cadmium plating of the forward four bolt holes was applied during production: No further action is required by this AD. If operator records indicate that during the inspection required by paragraph (a) of this AD cadmium plating was applied during production (not during rework or replating), no further action is required by this AD. (Indications of rework include oversized fasteners and/or fasteners with repair sleeves, and/or flap track dash numbers that have been changed per the service bulletin.) Compliance Time for Borescope Inspection (d) For airplanes on which cadmium plating of the forward four bolt holes was not applied during production: Do the action required by paragraph (e) of this AD at the later of the times given in paragraphs (d)(1) and (d)(2) of this AD. (1) Within 2 years or 2,000 flight cycles after the effective date of this AD, whichever is first; or (2) Within 6 years after doing the initial bolt hole rework per AD 91-03-17. Borescope Inspection (e) Do a borescope inspection of the forward four bolt holes on each side of the fail-safe bar of the flap tracks of the trailing edge flaps for discrepancies (corrosion, cracks, damaged cadmium plating), per Part 2 of the Work Instructions of Boeing Service Bulletin 747-57-2256, Revision 3, dated June 21, 2001. Then, do the actions specified in paragraph (e)(1), (e)(2), or (e)(3) of this AD, as applicable, and repeat the borescope inspection every 8 years or 8,000 flight cycles, whichever is first. Accomplishment of the actions specified in this paragraph terminates the requirements of paragraph (a) of this AD. Corrective Actions (1) If the cadmium plating is damaged, but no corrosion or cracking is found: Before further flight, do the eddy current inspection specified in and per Part 2.F. of the Work Instructions of the service bulletin. If no cracking is found, before further flight, cadmium plate the affected bolt holes per Part 2.F. of the Work Instructions of the service bulletin. (2) If any corrosion is found, before further flight, rework the affected bolt holes as specified in and per Part 2.G. of the Work Instructions of the service bulletin. (3) If any cracking is found, before further flight, repair per a method approved by the Manager, Seattle Aircraft Certification Office (ACO), or per data meeting the type certification basis of the airplane approved by a Boeing Company Designated Engineering Representative who has been authorized by the Manager, Seattle ACO, to make such findings. For a repair method to be approved by the Manager, Seattle ACO, as required by this paragraph, the Manager's approval letter must specifically reference this AD. Alternative Methods of Compliance (f)(1) An alternative method of compliance or adjustment of the compliance time that provides an acceptable level of safety may be used if approved by the Manager, Seattle ACO. Operators shall submit their requests through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, Seattle ACO. (2) Alternative methods of compliance, approved previously in accordance with AD 91-03-17, amendment 39-6884, are approved as alternative methods of compliance with paragraphs (a) and (b) of this AD. Note 2: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Seattle ACO. Special Flight Permits (g) Special flight permits may be issued in accordance with sections 21.197 and 21.199 of the Federal Aviation Regulations (14 CFR 21.197 and 21.199) to operate the airplane to a location where the requirements of this AD can be accomplished. Incorporation by Reference (h) Except as provided by paragraph (e)(3) of this AD, the actions shall be done in accordance with Boeing Service Bulletin 747-57-2256, dated March 8, 1990; Boeing Service Bulletin 747-57-2256, Revision 1, dated November 15, 1990; Boeing Service Bulletin 747-57-2256, Revision 2, dated March 5, 1992; or Boeing Service Bulletin 747-57-2256, Revision 3, dated June 21, 2001; as applicable. This incorporation by reference is approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies may be obtained from Boeing Commercial Airplane Group, P.O. Box 3707, Seattle, Washington 98124-2207. Copies may be inspected at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC. Effective Date (i) This amendment becomes effective on January 6, 2003. Issued in Renton, Washington, on November 19, 2002. Vi L. Lipski, Manager, Transport Airplane Directorate, Aircraft Certification Service. [FR Doc. 02-30026 Filed 11-29-02; 8:45 am] BILLING CODE 4910-13-P